TIDAL INFORMATION
The dominant tide in the Mumbai Harbour is the semi-diurnal tide with a period of 12 hours and 40 minutes. The following are the particulars of tidal levels related to Chart Datum.
Tide |
Above(+) or Below(-) Chart Datum |
Highest High Water recorded |
+ 5.39 m |
Mean High Water Spring Tides. |
+ 4.42 m |
Mean High Water Neap Tides. |
+ 3.30 m |
Mean Sea Level. |
+ 2.51 m |
Mean Low Water Neap Tides. |
+ 1.86 m |
Mean Low Water Spring Tides. |
+ 0.76 m |
Lowest Low Water recorded. |
- 0.46 m |
Highest Low Water |
+ 2.74 m |
Statistical studies made indicate that :-
WIND
General direction of wind is from the North to the West quarter, with seasonal variations as shown below :-
SEASONAL WIND VARIATIONS
Months |
Directions |
Speeds |
1. Feb-May |
Mainly from N.W. |
(Max. 8 to 10 Beaufort |
2. June-Sep |
Mainly from W.N.W. |
(Max. 8 to 10 Beaufort |
3. Oct-Jan |
Mainly from N.N.W. |
(Max. 6 to 8 Beaufort |
CYCLONES
These may occur in the period of May/June or October/November. The last severe cyclone off the coast of Mumbai was experienced in June 1996. Prior to this the earlier cyclone occured in 1992.
CURRENTS
The currents in the harbour are essentially caused by the tides and are not influenced to any extent by monsoons etc. The tidal flow is unsteady and the magnitude and direction of the current varies with respect to location, time and depth.
WAVES
The predominant waves are the swell waves generated by deep sea storms. These mainly arise just before and during the South West monsoon. The statistical analysis indicates that most wave periods fall between 6 seconds and 10 seconds.
During the continuance of the North-East monsoon, North-Easterly winds known as "Elephantas" blow for short durations during the months of October-November. As the fetch and duration of these winds are limited, the"Significant height" of the resulting waves is not likely to exceed 1 metre with period ranging from 3 to 5 seconds.
RELATIVE HUMIDITY & TEMPERATURE
Relative humidity ranges from 61% to 87% being the highest in the monsoon period. During the winter months (Nov-Jan) relative humidity ranges from 61% to 72%. Mean daily temperature ranges from 24 Degrees C to 33 Degrees C except during the winter period when the minimum temperature may fall to about 19 Degrees. The hotter months are March, April, May and June.
VISIBILITY
In general, on the West Coast, above latitude 16o N mist sometimes develops during sunrise but disperses thereafter.
At Mumbai from November to March smog hangs over the land, obscuring everything in view. This happens only for short periods most often shortly after sunrise but also occasionally in the evenings. Visibility is generally good for most part of the year.
RAINFALL
The climate of the region has a regular seasonal variation determined by the occurrence of two annual monsoons. The South-West monsoon period extends from June to September. Most of the annual rainfall occurs during the South-West monsoon, the average monthly rainfall being about 45 cm.Rain during the North-East monsoon is slight. The average annual rainfall over 20 years is 193 cm.